Docker MCP Gateway: Argument injection via OCI image label YAML

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.7 · CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H · score source

EPSS

• CVE-2026-55887: 0.22% estimated exploitation activity in the next 30 days; percentile 12.89 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A maliciously crafted OCI image label can inject arbitrary arguments into the docker run command line constructed by the MCP Gateway. An attacker who controls an image that the victim references via docker://, or that the victim's catalog pulls a snapshot from, can mount the host filesystem, run as UID 0, and execute arbitrary code on the host. Details The io.docker.server.metadata OCI image label is YAML-unmarshalled directly into the wide catalog.Server struct, which carries runtime-shaping fields (Volumes, User, Command, ExtraHosts, AllowHosts, DisableNetwork, Env, Remote, SSEEndpoint, OAuth,Secrets, LongLived, Policy) alongside descriptive fields. Every runtime field carries a YAML tag, so the unmarshal mass-assigns from the attacker-controlled label content; only Image is overwritten afterwards. The gateway's container-launch code then appends those fields verbatim as docker run flags (-v, -u, --add-host) with no allowlist or origin check, and execs docker with the…

Published by the source

18 Jun 2026, 13:05 UTC

Last modified by the source

18 Jun 2026, 13:05 UTC

Source last checked

26 Oct 2026, 15:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-r2xf-7jw5-pjg6

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# Patch Next advisory brief: CVE-2026-55887

Advisory: Docker MCP Gateway: Argument injection via OCI image label YAML
IDs: CVE-2026-55887, GHSA-r2xf-7jw5-pjg6
Record: https://patchnext.com/advisories/cve-2026-55887 (revision 1, source checked 26 Oct 2026, 15:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/docker/mcp-gateway 0.42.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/docker/mcp-gateway: affected >= 0.21.0, < 0.42.2; fixed in 0.42.2

## Suggested inspection (read-only)
- Go github.com/docker/mcp-gateway: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/docker/mcp-gateway.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-r2xf-7jw5-pjg6 (GitHub-reviewed advisory GHSA-r2xf-7jw5-pjg6 lists affected ranges: Go github.com/docker/mcp-gateway >=0.21.0 <0.42.2)

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